[vtkusers] Slight Change to Clipping Planes

[John Biddiscombe]

Hello All,

Clipping planes have moved from AbstractMapper3D to AbstractMapper (to 
allow 2D mappers to use the same interface). This also involved moving 
vtkPlanes into common from graphics, which in turn meant removing one 
function from vtkPlanes
vtkPlanes-> void SetFrustumPlanes(float aspect, vtkCamera *camera);
is now no longer available. vtkCamera belongs in Graphics and caused a 
dependency problem when included in the above function.
A new function can be used where the old one was...
vtkPlanes-> void SetFrustumPlanes(float aspect, float planes[24]);

so code can be reworked from

planes->SetFrustumPlanes(aspect, camera);

to

float aspect, planes[24];
camera->GetFrustumPlanes(aspect, planes);
planes->SetFrustumPlanes(aspect, planes);

unfortunately, this may break some tcl scripts, but it is unlikley that 
anyone was depending on this.

Thanks

John B